LING 408/508: Computational Techniques for Linguists. Lecture 21

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1 LING 408/508: Computational Techniques for Linguists Lecture 21

2 Administrivia Both Homework 7 and 8 have been graded Homework 9 today

3 Example: example.cgi SiteSites$./example.cgi Content-Type: text/html; charset=utf-8 <html><head></head> <body><h1>~sandiway/sites/example.cgi</h1> <p>now: Tue Oct 30 20:37:01 MST 2018 </p> <p>user: sandiway </p> <script src="canvasjs.min.js"></script> <div id="cc" style="height: 400px; max-width: 600px; margin: 0px auto;"></div> <script> window.onload = function() { var chart = new CanvasJS.Chart("cc", { animationenabled: true, title: { text: "Disk Space: MB" }, data: [{ type: "pie", startangle: 240, yvalueformatstring: "##0.00'%'", indexlabel: "{label} {y}", datapoints: [ {y: / *100, label: "Used", color: "Bisque"}, {y: / *100, label: "Unused", color: "Tan"} ]}]} ); chart.render(); } </script></body></html>

4 Example: example.cgi $2 $3 $4

5 Example: example.cgi Used the free(?) canvasjs.min.js library from They have source code for many examples of javascript charts. Wondering what happens after 30 days

6 Today's Topics Sending form data to the webserver using: 1. GET method 2. POST method There are also (many) other methods to communicate information depending on the kind of webserver we run: e.g. Apache Tomcat (for Java) e.g. WebSocket interface (for bidirectional data passing) etc.

Sending information using GET HTML form: 1. <form action="http://localhost/cgi-bin/get.cgi" method="get"> 2. First: <input type="text" name="first" size=12> 3.

7 Sending information using GET HTML form: 1. <form action=" method="get"> 2. First: <input type="text" name="first" size=12> 3. Last: <input type="text" name="last" size=12> 4. <input type="submit"> 5. </form> Information encoded using alphanumeric characters: why? URLs are restricted to alphanumeric characters only bash accesses the URL-encoded string via the environment variable QUERY_STRING

8 Sending information using GET get.cgi: 1. #!/bin/bash 2. echo "Content-Type: text/plain" 3. echo 4. #echo $QUERY_STRING 5. origifs=$ifs 6. IFS='=&' 7. set -- $QUERY_STRING 8. IFS=$origIFS 9. echo "1:<$1> 2:<$2> 3:<$3> 4:<$4>" = and & In bash: IFS = internal field separator (for arguments) default: space newline tab set -- String -- option: positional parameters $1,$2,..etc. are set after splitting String

9 Sending information using GET get.cgi: #!/bin/bash echo "Content-Type: text/plain" echo #echo $QUERY_STRING origifs=$ifs IFS='=&' set -- $QUERY_STRING IFS=$origIFS echo "1:<$1> 2:<$2> 3:<$3> 4:<$4>"

10 Sending information using GET OS X /Library/WebServer/CGI-Executables/ $ls -l get.cgi Ubuntu /usr/lib/cgi-bin/ -rwxr-xr-x 1 root wheel 161 Oct get.cgi sudo chmod 755 get.cgi

11 Sending information using POST

12 Sending information using POST HTML form: 1. <form action=" method="post"> 2. First: <input type="text" name="first" size=12> 3. Last: <input type="text" name="last" size=12> 4. <input type="submit"> 5. </form> bash accesses the URL-encoded string on standard input via read cf. GET using QUERY_STRING

13 Sending information using POST bash accesses the URL-encoded string on standard input via read read.cgi: 1.#!/bin/bash 2.echo "Content-Type: text/plain" 3.echo 4.read input 5.origIFS=$IFS 6.IFS='=&' 7.set -- $input 8.IFS=$origIFS 9.echo "<$2><$4>"

14 Sending information using POST Client-side code: Server-side code: read.cgi: 1. #!/bin/bash 2. echo "Content-Type: text/plain" 3. echo 4. read input 5. origifs=$ifs 6. IFS='=&' 7. set -- $input 8. IFS=$origIFS 9. echo "<$2><$4>"

15 Limitations of positional parameters set values: origifs=$ifs IFS='=&' set -- $QUERY_STRING IFS=$origIFS echo "1:<$1> 2:<$2> 3:<$3> 4:<$4>"

16 Files and Locations Server cgi-bin directory: MacOS: /Library/WebServer/CGI-Executables Ubuntu: /usr/lib/cgi-bin Webserver logs: MacOS: /var/log/apache2/error_log Ubuntu: /var/log/apache2/error.log Course webpage: form-get.html form-post.html get.cgi read.cgi (needs 755 permissions) (needs 755 permissions)

17 Error Log Example: error log: [Wed Oct 31 22:08: ] [cgi:error] [pid 4600] [client ::1:51340] AH01215: (13)Permission denied: exec of '/Users/sandiway/Sites/get2.cgi' failed: /Users/sandiway/Sites/get2.cgi [Wed Oct 31 22:08: ] [cgi:error] [pid 4600] [client ::1:51340] End of script output before headers: get2.cgi

18 Homework 9 Use the cgi-bin methods to implement a BMI bash shell script on the webserver. i.e. you should modify your BMI program to accept data from a html form and compute the value on the server side Use both GET and POST methods to communicate the weight, height and units. Submit your.html and.cgi files Submit screenshots to show it working in both cases Due next Monday by midnight

19 Example: adding names to a server list Normally, you'd set up database software,e.g. mysql, on the webserver

20 Example: adding names to a server list Server-side code: get2.cgi Client-side code: addnames.html Data file: touch names-list.txt chmod a+w names-list.txt

LING 408/508: Computational Techniques for Linguists. Lecture 20

LING 408/508: Computational Techniques for Linguists Lecture 20 Today's Topic Did everyone get their webserver (OS X or Ubuntu or both) up and running? Apache2 Last time: we configured the root site http://localhost/